CubebInputStream.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

#ifndef DOM_MEDIA_CUBEBINPUTSTREAM_H_

#define DOM_MEDIA_CUBEBINPUTSTREAM_H_

#include "CubebUtils.h"

#include "mozilla/Maybe.h"

#include "mozilla/RefPtr.h"

#include "mozilla/UniquePtr.h"

#include "nsISupportsImpl.h"

namespace mozilla {

// A light-weight wrapper to operate the C style Cubeb APIs for an input-only

// audio stream in a C++-friendly way.

// Limitation: Do not call these APIs in an audio callback thread. Otherwise we

// may get a deadlock.

class CubebInputStream final {

 public:

  ~CubebInputStream() = default;

  class Listener {

   public:

    NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING;

    // This will be fired on audio callback thread.

    virtual long DataCallback(const void* aBuffer, long aFrames) = 0;

    // This can be fired on any thread.

    virtual void StateCallback(cubeb_state aState) = 0;

    // This can be fired on any thread.

    virtual void DeviceChangedCallback() = 0;

   protected:

    Listener() = default;

    virtual ~Listener() = default;

};

  // Return a non-null pointer if the stream has been initialized

  // successfully. Otherwise return a null pointer.

  static UniquePtr<CubebInputStream> Create(cubeb_devid aDeviceId,

                                            uint32_t aChannels, uint32_t aRate,

                                            bool aIsVoice, Listener* aListener);

  // Start producing audio data.

  int Start();

  // Stop producing audio data.

  int Stop();

  // Gets the approximate stream latency in frames.

  int Latency(uint32_t* aLatencyFrames);

 private:

  struct CubebDestroyPolicy {

    void operator()(cubeb_stream* aStream) const;

};

  CubebInputStream(already_AddRefed<Listener>&& aListener,

                   UniquePtr<cubeb_stream, CubebDestroyPolicy>&& aStream);

  void Init();

  template <typename Function, typename... Args>

  int InvokeCubeb(Function aFunction, Args&&... aArgs);

  // Static wrapper function cubeb callbacks.

  static long DataCallback_s(cubeb_stream* aStream, void* aUser,

                             const void* aInputBuffer, void* aOutputBuffer,

                             long aFrames);

  static void StateCallback_s(cubeb_stream* aStream, void* aUser,

                              cubeb_state aState);

  static void DeviceChangedCallback_s(void* aUser);

  // mListener must outlive the life time of the mStream.

  const RefPtr<Listener> mListener;

  // So must mCubeb (mStream has a bare pointer to cubeb).

  const RefPtr<CubebUtils::CubebHandle> mCubeb;

  const UniquePtr<cubeb_stream, CubebDestroyPolicy> mStream;

};

}  // namespace mozilla

#endif  // DOM_MEDIA_CUBEBINPUTSTREAM_H_